Filed: Southern California

The latest expected track for Hurricane Miriam is very favorable for Southern California. As of 8:00 a.m. PDT Miriam has become a major hurricane of category 3 strength, with maximum sustained winds of 120 mph, and is currently moving NW at 12 mph. The official forecast expects Miriam to gradually turn northward and decrease in speed over the next few days, with possible further intensification over the next 12-24 hours.

While the storm is already located in the Southern California swell window, the northward (possibly northeast) turn would focus more swell energy towards Southern California, which is good news for spots that favor moderate-period, south to southeast swell. Keep an eye on the Point Loma forecast and real-time reports, particularly mid-week, which is when the swell’s initial impact is expected to arrive.

Hurricane Miriam has started to weaken, with maximum sustained winds now in the 105 mph range (category 2). Additional, slow weakening is expected over the next 48 hours, with hurricane force winds extending outward up to 35 miles from the center. Microwave images indicate that the inner eyewall has collapsed, and the storm has taken on an asymmetric structure, likely due to southwesterly shear. Miriam is still expected to slow and turn north within 48-72 hours, at which time it should weaken below hurricane strength.

As a result of the latest observations, the official forecast has been slightly downgraded. Unfortunately, this means the surf forecast should be downgraded as well. It would have been nice to have major hurricane strength persist as the storm slowed and turned towards California, but it’s looking like Miriam will only make a modest, moderate-period SSE impact later this week.

Hurricane Miriam remains a category 2 storm, with maximum sustained winds near 100 mph. The forward speed of the hurricane has been slowing over the last 12-24 hours, and Miriam is currently moving west-northwest at 5 mph. A turn toward the northwest is expected later today, followed by a turn to the north-northwest on Wednesday. Hurricane force winds extend outward up to 35 miles, and tropical storm force winds extend outward up to 115 miles.

The decrease is tracking speed is favorable news in terms of swell production, as is the forecast path, however gradual weakening is expected to continue during the next 48 hours. A mixture of swell periods and directions are clearly visible in Wednesday’s San Clemente Basin forecast, with moderate WNW swell (4-5 feet at 12-13 seconds, 293°), moderate SSW swell (2 feet at 13 seconds, 203°), and moderate SSE swell from Miriam (2-3 feet at 12 seconds, 161°) all concurrently in the water.

Two things to note: (1) Buoy 46086 is located well offshore, and is exposed to much more swell energy than nearshore stations, so observations will be greater than those located closer to land. (2) Real-time primary swell reports over the next few days will likely be dominated by the longer-period WNW and SSW groundswells, but don’t be fooled, the SSE energy is still in the mix, it just isn’t expected to be dominant.

With all that energy in the ocean, expect some fun-sized combo-swell conditions on Wednesday and Thursday, but don’t expect to be sharing epic tales of Miriam with the kids twenty years from now. To truly make the most of the combo-swell conditions, you’ll need to find a spot with exposure to the WNW and SSE angles at moderate swell periods (think Dana Point and Oxnard), otherwise go with the SSE/SSW breaks.

The long range forecast for the South Pacific is currently showing a potential swell that, if the model holds together, would deliver waves to Southern California during the latter half of the Labor Day weekend. The 180-hour outlook has been a bit agressive this summer, with storm systems falling apart before really reaching their potential, so don’t get too excited just yet.

Update as of August 22, 2012 at 23:00 PDT – What were we saying about downgrades? The expected swell height (132 hour run) is shown below. Still, it’s better than nothing and actually above average for this bummer of a summer.

Hurricane Emilia entered the Southern California swell window yesterday at Category 2 strength, but continued to intensify overnight, reaching Category 4 status with maximum sustained winds of 140 mph. As of 8:00 a.m. PDT (NHC Advisory #12), Emilia is moving west-northwest (285°) at approximately 10 mph, with hurricane force winds extending outward up to 35 miles. Emilia is expected to gradually weaken beginning tonight, and continue weakening through Thursday, July 12th. The track model guidance predicts continued west-northwest movement, with a late westward turn, with only a slight change in speed.

The image above includes the best track data for Hurricane Eugene (2011), which entered the Southern California swell window on August 2, 2011 as a Category 2 hurricane and later intensified to Category 4. Looking at the historical wave observation data from the Point Loma station on Friday, August 5, 2011, reveals a steady pulse of South energy in the 3-5 foot at 13-15 seconds.

Primary Swell at Point Loma – Friday, August 5th, 2011

Although a northerly track is more favorable for Southern California surf production (the majority of a hurricane’s swell energy is focused along its path), Emilia is moving WNW at a slightly slower pace than Eugene did (10 mph vs. 14 mph), which gives the wind more time to transfer energy onto the sea surface. The latest forecast model for the Point Loma buoy shows a small, moderate-period SSE pulse arriving Thursday (July 12, 2012), with continued moderate south swell through the weekend (3 feet at 10 seconds). However, I wouldn’t be surprised to see an upgrade in the forecast, particularly for late Thursday into Friday, if Emilia maintains major hurricane strength and a relatively slow pace (10 mph or less).

Point Loma, CA – 5-Day Forecast as of 11 p.m. on July 9, 2012

I’d recommend keeping an eye on the Point Loma 5-day forecast over the next few days to see how things shape up. Given how dismal this summer has been so far in California, it’s definitely something to get excited about. Just how excited depends on what Emilia does in the next 24-48 hours.

“You should’ve been here yesterday!” We’ve all heard it, and hopefully you’ve had the luxury of saying it, but how do you actually quantify the conditions at your local break? One of the advantages of recording the observational swell data provided by ocean buoys is that it allows us to reference historical reports and plot them over time as well as location.

Having recently moved to Los Angeles from Hawaii, I’m still getting a feel for the region and how swell energy impacts the coast. Compared to my experiences on the North Shore of O‘ahu, the waves in Southern California tend to come off a bit soft. But how soft? How do you measure the relative strength of the two regions?

To satisfy my curiosity I’ve built a monthly wave power almanac, which displays the maximum wave power per month, as well as the average. The background color indicates scale, with white being the least powerful and deep purple being the most powerful. The two stations I’ve chosen to look at are Dana Point in California and Waimea Bay in Hawaii. Let’s begin with the Dana Point buoy.

Dana Point, California - Primary Swell Power (April 2012 - May 2010)

The first month that stands out is September 2011, it’s the lone green block with a maximum of 48. Guess what swell that was (unsure?). While it wasn’t nearly as deadly by the time it crossed the Pacific, the “Code Red” monster from Tahiti is still the most powerful event on the buoy over the past 24 months. April 2012 is actually the second most powerful at 37, likely as a result of the large NW swell that pushed through at the beginning of the month.

Aside from those two, no other month surpasses 30, although there are a few high 20s. The least powerful month was October 2010, which recorded a measly maximum of 8. As we move on to the Waimea Bay buoy, things starts to get a bit more colorful.

Waimea Bay, Hawaii - Primary Swell Power (April 2012 - May 2010)

Let’s start off with July 2011. It had a maximum wave power of 2. Why do you think everyone jumps on their stand-ups and paddleboards on the North Shore during the summer? There’s literally nothing to surf.

It’s an entirely different ocean just six months earlier. January 2011 packs the most mana, with a recorded maximum wave power of 218. That’s over four times more powerful than anything recorded by the Dana Point buoy in the last 24 months. In fact, the average wave power during that month was 30! Definitely a stellar month, as well as a stellar 2010-2011 season for Hawaii.

You’ll also notice that with the Pipe Masters running in December, the ASP has kinda been missing out these last two years. January and February of both 2011 and 2012 have been about twice as powerful as December. Both the Backdoor Shootout and the Volcom Pipe Pro scored ridiculous surf this past year, with the latter actually stopping competition because Pipeline got too big.

Having access to data like this helps put things into perspective and identify those truly special “should’ve been there” moments. It also provides a frame of reference for future conditions, when similar calculations are applied to forecast models. Of course there are plenty of other factors that can influence the quality of the surf, but if the power is there, there’s potential.

The forecast is looking very good for the next five days, with a combination of long-period swells expected from both the south and the west-northwest.

Currently, moderate SSW leftovers in the 2 feet at 13 second range are lingering throughout the region, but a new WNW swell is already making its way down the coast, with more northerly stations reporting a solid 12 feet at 14-15 seconds. Looking at the forecast for the Harvest station (above), you can see that the new WNW swell should peak at that location by early Thursday morning (12 feet at 13 seconds, 293°).

As that WNW pulse fades into the weekend, an even bigger swell arrives right on its heels, with swell conditions currently expected to reach a substantial 21 feet at 14 seconds (299°). If swell heights do top 20 feet at the station on Sunday, it will be the first time it’s done so in over a year. The bad news is that strong NNW winds (29 knots, 30+ mph) are also forecast and will likely provide victory at sea conditions for the most exposed breaks.

However, there is also a solid south swell forecast to peak on Saturday, with 17+ second long-period forerunners expected as early as Thursday. Conditions are looking really fun for Friday afternoon, with light winds and a building ground swell. Swell conditions peak at the Point Loma South station (above) on Saturday in the 4 feet at 17 second range (198°), but west to northwest winds increase throughout the weekend, so the best bet is to get it early.

Best Bet: Spots that like long-period southwest swell (4 feet at 17 seconds, 195-198°) on late Friday or early Saturday.

Wildcard: Spots that favor combo-swell conditions (long-period southwest and west-northwest) on Sunday, but find some shelter from the NNW winds or it’s a bust.